SYNTHESIS OF INFECTIOUS TRANSCRIPTS OF BLUEBERRY SCORCH CARLAVIRUS IN-VITRO

Blueberry scorch carlavirus (BBScV) is a filamentous virus with a poly adenylated, positive-sense RNA genome. A near full-length cDNA clone o f BBScV was constructed by assembly of clones from a cDNA library. To generate a full-length cDNA clone, the 5' terminus was mutagenized by PCR to introduce nucleotides present in the wild-type virus and not in the near full-length clone, and then fused directly to the T7 bacteri ophage RNA polymerase promoter at the 5' terminus. Capped and uncapped BBScV transcripts were synthesized in vitro from the full-length cDNA clone. Capped transcripts were infectious, producing systemic symptom s identical to those caused by the wild-type virus following inoculati on onto Chenopodium quinoa leaves. Uncapped transcripts were substanti ally less infectious than capped transcripts. This represents the firs t report of infectious transcripts for a member of the carlavirus grou p.